Field of the Invention
The invention relates to a switched-mode power supply with sinusoidal current consumption, having a rectifier to which a sinusoidal alternating voltage can be supplied and having an output at which a rectified alternating voltage can be picked up, the alternating voltage is delivered to a switched controller, and a multiplier device receives the input signal and the output signal of the switched controller, multiplies the two variables and generates an output signal being supplied to the switched controller.
One such switched-mode power supply (SPMS) is known, for instance, from U.S. Pat. No. 4,677,366. An SPMS with sinusoidal current consumption includes a pilot control unit being used to relieve a voltage regulating circuit. A typical configuration of that kind may be found in the publication entitled: Unitrode-Datenbuch, Anhang [Unitrode Manual, Appendix], Chapter 6, pp. 6-1 to 6-16. One learns from both references that a result of a theoretical derivation of the above-mentioned pilot control function is that a pilot control variable V.sub.in must be exactly squared and in this regard reference is made to FIG. 6 on pages 6-8. A basic circuit diagram for such a configuration is shown in and described below with reference to FIG. 3.
The realization of such a circuit requires a so-called slope multiplier, for performing the squaring. That makes the overall expense for circuitry relatively high, but an exact square dependency of V.sub.in as a pilot control variable has some practical disadvantages as well. For instance, in power supply networks with a regulation of consumption through the voltage amplitude, the current consumption at low voltages will rise more and more in the event of a brownout. That is common, especially in the United States.